Quenching fluid



Patented July 5, 1927.

UNITED STATES PATENT OFFICE.

GUY M. BALL, 0]? DAYTON, OHIO.

omen-came FLUID.

No Drawing. Application filed July 25, 1924, Serial No. 728,185. Renewed December v9, 1926.

This invention relates to a quenching fluid to be used in hardening ferrous or cuprous metals.

The primary object of the provision of a quenching fluid for use in hardening metals of the above type, which has the nature of being able to very ra )idly cool the metal after it has been plunge into the solution, and of cooling the metal so that it will not warp or buckle.

I have found that a quenching fluid con sisting of two pounds sodium chloride, onequarter pound potassium cyanide, one pound borax, to one gallon of water gives a fluid having superior properties as a quenching fluid for the hardening or tempering of wrought steel, cold rolled steel, wrought iron, and brasses and bronzes. In place of sodium chloride, the potassium salt may be used. Sodium cyanide may also be used in place of the potassium cyanide, as the salt of these two metals, sodium and potassium, have similar qualities. The solution is also applicable for the treatment of any other metals, the properties of which are improved by rapidly cooling in a quenching liquid. The solution is not applicable however to metals such as zinc or alloys of the same, which will be rapidly corroded and dissolved, to a large extent, when they come in contact in a heated condition with the fluid.

The solution according to the formula given in the preceding paragraph, whenfirst made, gives off a gas which has been found to'be harmless to the user, but after a few hours the solution becomes. stabilized, and after that time, when a heated piece of metal is plunged into it, no more dissipation. of gas takes place.

The proportions as above mentioned produces a substantially saturated solution of the salts which will be,of an alkaline nature, due to the presence of the borax. The chemical term for the borax is either sodium biborate or sodium pyroborate. It is not necessary to exactly follow the proportions as given, however, it is desirable to have sufiicient amounts of the various ingredients so as to form practically saturated or even a super-saturated solution, in order to obtain the best results. The amount of salt present exceeds the combined weight of the potassium cyanide and the borax as will be noted.

It has been found by actual test that low carbon steels, which are ordinarily diflithis invention is cultly tempered, are greatly hardened and tempered by being first heated to a dark' cherry, red color and then plunged into'the solution as above outlined. A bronze specimen has been found to cool after being immersed for one second in my quenching fluid, so that in that length of time it is at a lower temperature than a similar specimen under similar conditions which is plunged into a brine solutionand held there for five or six seconds.

A solution prepared in accordance with my invention has qualities which equal and in some cases exceed that of oil as a quenching fluid 'as regards warping and buckling, together with the added advantage of very rapid cooling. The heat transfer from the heated specimen to the uenching fluid takes place with my improve solution so evenly and rapidly that there is very little tendency for the specimen to buckle even though it is of very thin material. The rapidity with which the heat dissipation takes place, permits results to be obtained so that the physical properties of the metal, after being so quenched, greatl exceed those which may be obtained by t e use of other known formulae.

When the heated specimen is plunged into the quenching solution, the reaction atfirst is quite violent due to. the boiling of the liquid immediately surrounding the specimen, but this reaction and turbulence in some manner appears to aid in the rapid transfer of heat. With a saturated solution as before mentioned, there appears to be no formation ofsteam bubbles which have been thought to cause the buckling effect of brine solutions. Where a specimen is plunged into a brine solution it is evident that some portions of the specimen immediately after being plunged are contacting with a body of steam, while other portions are contacting with the liquid itself, and an uneven cooling will take place, which will cause a war ing or buckling effect. It is a comparative reedom from this effect which makes the quenching solution of my invention particularly desirable.

I claim:

1. A quenching solution for hardening metals, consisting of alkaline saturated Water solution of salt, potassium cyanide, and borax.

2. A quenching solution for hardening metals, consisting, of a concentrated Water solution of salt, potassium c snide, and horex the weight of salt excee ing the combined.

fineness ingredients in the op roximate ratio named: sodium chloride, 2 1 s.; potassium cyanide, 170.; borex, 1 1b.;water, 1 gal.

- 5. A quenching solution for hardening ferrous or cuprous metals comprising sodium chloride 2 pounds, potassium cyanide 4 -pound, borax 1 pound, and water 1 gallon.

In testimony whereof I afiix my signature.

GUY M. BALL. 

